High-speed tractor



Feb. 21, 1928.

- I W. H. SMYTH HIGH SPEED TRACTOR Filed March 28, 1922 INVENTOR Patented Feb. 21, 1928.

PATENT OFFICE.

WILLIAM H.-SMYTH, or BERKELEY, CAL FORNIA.

men-SPEED TRACTOR.

Application mea march 28, 1922. 'Serial No. 547.42%.

My invention relates to self-laying track vehicles. It has as its main object 'to provide such constructive f-t'eatures and arrange ments in the load-hearing track assembly as will permit, in this character of device, speed or travel comparable 'to that'of the round wheel type. And to accomplish this main purpose by means so simple and 'eflicient as to increase the effective life and smoothness of operation, while reducing the frictional wear and losses of power, the

breakage of 'parts,fupkeep expense and ini tial cost of this character or "vehicle.

To this general end, a more specific object of my invention is to provide a smootlnfundistorted track for the load-bearing -trackw'heels, a track which cannot kink between the load-bearing points of wheel and track contact.

Another specificobject is to provide means whereby the Y track-chain is automatically kept under local resilient tension at the points where, in the lower run of -'t'he =ch'ain, ground obstruction kinking occurs under present practice, and similar means to avoid the fiddle-string chain je rking in the upper run, incident to intermittent support and general tensionin'g by i'or'ci ble adjustment or the idler wheel as at present practi'ced.

A further specific object is to provide anti-friction means at points of present excessive wear and breaka'ge where, under the constructions of practice prior to this disclosure, anti-friction means are imp'r'acticable. 7 I

-A typical expression of my invention which accomplishes all these noveland high ly important objects is shown in the accompanying drawing wherein! V Fig. 1 shows a side elevation; parts-otthe chain-track being omitted for'simplicity and clearness of illustration Fig. 2 on a "larger scale, a dotted line a; of Fig. 1; Fig. '3 a corresponding section on dotted ,section V on line 1 Fig. 4 a horizontal section of "a length of track-chain. V

The arrows in Fig. 1 indicate direction or" motion.

The track-chain assembly alone short disknowledge of mechanics skilled in "this art,

I have hereinafter confined my description to those parts directly affected by my in-' vention, for simplicity in the dr a-wing,, w i-th enhanced clarity in the specification. But,

I in what follows, it is to 'be understood, inthe drawing, description, and claims, that the sprocketed power-wheel with its shaft, .jourrial-box, and indicated frame,'as designated and illustrated, areintended to represent, not alone apower-whee'l but the motor element complete with any suitable frame mounting or connection between the ,power element and the track-chain assembly.

With this understanding, A represents the frame-work pertaining to a self-layingtrack 'motor vehicle. It carries journal box B, shaft (3, power-wheel D with its circumferen'tial teeth or sprockets d, and idler F with its raised centrally disposed circumferent'ial flange e.

Encircling the whee-1D and idler Fis the, preferably double-rail, endless track-chain G composed of links 19 which chain will later be 'parti'cularized.

H-H, are load-bearing track-wheels they are suitably j ournalled at a in a portion of the framework shown as a" depending bracket A secured to A. The bracketA and, Wheels H 111, journalled the1'ein,lare shown in Fig. 1, and in Fig. 2, the wheels H-H are shown travelling upon andbeing supported by the double rails of the chain.

A is provided witha rib or the like 2& extending downward into the space between the chain-track rails. To A is secured a resilient local control and chain guide, shown as a leaf-spring 1, between the rails. The spring-guide I extends fore-and-aftto within a short distance respectively, of the peripheries of sprocket-wheel D and idler F, constituting a lower resiliently flexible chain-track for the ground-run of chain G, and also an effective trash-excluding cover for the functioning interior parts of the endless chain during its ground contact. The leavesof spring I are normally straight, or only very slightly curved, but when in position, as shown, they exert local tension upon and furnish lateral guidance to the chain.

A is a part of the framework suitably located, as shown in Fig. 1 to sustain a, preferably resiliently adjustable, T-headed tension bar J. For the adjustability of J, is shown the rod j which is threaded into the shank J of the T-bar, and it is provided with a radially perforated or socketed boss 7' resting upon a stiff coil tension spring J encircling j and abutting upon the base of A Secured upon the T-head of tension bar J another spring-guide is mounted, in many respects similar to I, but supporting and tensioning the upper run of the endlesschain-track, thus I constitutes, with its adjustable support J, a general as well as a local automatic tension, upperflexible chaintrack.

The endless track-chain G consists of ground contact tread-shoes g-g of suitable" dimensions, not shown in Fig. 1, but clearly shown in Figs. 2 and 8. Secured to the upper surface of each shoe 9 are two l nks -9 constituting adjacent track sections with extended rail-heads 9 -9 having parallel inner and outer edges. Other than being (when made, as shown), right-andleft, the links g g are substantially similar in construction, and each is provided with hinge connections to unite them and successive links into the flexible endless chain G. An element of each hinge connection is a loose rollable pin 9 extending transversely across from link to link.

An anti-friction bearing, shown as a short roller K is in contact with each hingepin g approximately of the same diameter so they roll upon each other adjacent to the hinge center of motion-the dotted line '2 Fig. 4E. The anti-friction rollers are enclosed in a dirt-excluding shell g made up of the overlapping co-acting ends 9 and g of succeeding links, as shown in Fi 4.

An additional anti-friction provision is a roller L loosely journalled upon the pin g in the space between the adjacent parallel link rail-heads 9 9 These rollers L-L are of such diameter that they do not contact with the guide-member I when they are travelling upon smooth ground and they are passing beneath the load-bearing trackwheels 11-11, but are sufficiently close to prevent upward kinking of the chain at its hinges between the load-bearing points of track-wheel and track contact. The rollers LL also serve the additional function of anti-friction sprocket-abutments, co-acting anti-frictionally with the sprockets al -def the power-wheel D, and rolling when occav sion requires upon the raised central flange e of idler E regardless of the idlers direction of rotation.

The outer side of each shell-enclosure g has an aperture adapted to permit the easy inspection or renewal of the pins g g and also the rollers KK. This renewal aperture is provided with a closure, shown as a slidable bevelled edged plate M seated in a bevelled edged groove m and flush with the outer surface of the link, as shown in Figs. 2, 3 and 4. The plate M is preferably made a loose fit for its groove and then slightly bent to give it a rather tight torsional fit when in place.

In operation the load-bearing track-wheels.

normally bear the entire weight of the machine with its motor element etc. When encountering a ground obstruction the trackchain G gives with a resiliently controlled curving flexure, without the strain of sud? .denly destructive kinking, as the anti-friction rollers LL roll smoothly upon the local tension spring guides I and the spring returns the chain in like progressive manner to its normal path without jerk or jolt when the obstruction is being passed.- This local resilient automatic control is effective both in front and at the rear, that is to say when the tractor is meeting and when leaving an obstruction. And when an extraordinary obstruction is encountered the chain'is free to correspondingly respond by therupper,

flopping, carpet-shaking jerky motion which grows to a practically prohibitive degree as speed is increased, under present. general practice and construct on. But by the local Hit) 7 automatic tensioning provisions of the present invention, these highly deleterious effects are avoided. The spring-guidesI -I receive and cushion the track-chain immediately, before flop or jerk can be generated.

And, by the. co-action of the anti-friction rollers LL and the instantly responsive spring-guide supporting-track, the trackchain G runs smoothly'from sprocket-wheel D to idler E and from idler to sprocket wheel practically regardless of speed.

By practical experience it has frequently been demonstrated that comparatively large and massive load-bearing-wheels HH are necessary: small chain-carried rollers while in many ways advantageous as anti-friction means alone, have proved impractical as load-bearing track-wheels for general tractor service, under the conditions to be met and surmountedrbyfthe' groundau-nrof sel'fslaying egthe ground rrun of the'chaimicoisupport 'it'lle'l track-chain...

i. The: {destructive uncushifoned pounding,;;the=high-.rotationah speed'zdue. to.

small diameter: and ground conditions(make? their. -servicze'able; life I an'd.;.that:: oftheir: 'coacting gparts impractically short, and mega-'2 t1ve even their anti-friction functionrunder ing elements and provisions of the present invention. By this inventive division and appropriate distribution of function herein described, anti-friction rollers are restricted to'anti-friction functions for which they are inherently adapted; and to the massive load-bearing track-wheels are apportioned the heavy duty of resisting the pounding under load-carrying service, for which function they are inherently fitted, with the result that, owing to the present invention, greatly increased speed is no longer inhibited by the functional conflict that practically barsit under existing common practice and construction. I

The rails of self-laying-track vehicles being composed of a multitude of hinged sections the multitudinous joints are fruitful sources of much frictional power losses, great upkeep expense, and comparatively slow speed is made practically compulsory. By the simple and inexpensive anti-friction roller K of the present invention with its coacting easy inspection provision, the ready and practically costless renewal provision,

friction losses are reduced to aseemingly irreducible minimum; and the main object of high speed is thereby practically attainable.

In view of these radical and pioneer departures from present accepted practice, I do not desire to be limited to the particular expressions of my invention used herein for illustrative purposes, norlimited in any way framework, antifniction i'ollerssjournalledionzz the; chain below. its; ;track-surface,r+anch a grounderune schainrcontrol :,-tra"clr:V;:c-ioaoting:,1. with the rollers to limit the verticalamoverc ment :and; kinking of Ethe chain? 5.

2. i&-fl'3(ifi0l .comprising frameworkgioans s endless: t-rackechain; its "lower zruncadap ted L to;

ground-pa; support; vatrackewheelsr;.5 travel'ahlei upon the ground run of the chain to support the framework, antifriction rollers journalled upon the chain below its track- Is'urface, and resilient means coacting with the rollers to control the upward flexure of the chain.

3. A tractor comprising framework, an endless track-chain its lower run. adapted to ground support, track-wheels travelable upon the ground run of the chain to support the framework, antifriction rollers journalled on the chain below its track-surface, and atrack coacting with the rollers to'support the upper run of the chain.

4. A tractor comprising framework, an endless track-chain its lower run adapted to ground support, track-wheels travelable upon the ground run of the chain to support the framework, antifriction rollers journalled on the chain below. its track-surface, and an adjustable track coacting with the rollers to support the upper run of the chain.

5. A tractor comprising framework, an endless track-chain its lower run adapted to ground support, track-wheels travelable upon the ground run of the chain to support the framework, antifriction rollers journalled on the chain below its track-surface, and a resiliently adjustable track coacting with the rollers to support the upper run of the chain.

6. In a tractor comprising a frame with an endless-chain of hinged shoes adapted to ground support provided with twin-track rails raised above the inner surface of the shoes and twin track-wheels travelable upon the ground rum of the rails, flexibly resilient means coacting with the twin track-rails adapted to guide the ground run of the endless-chain track and control its flexure.

7. In a tractor comprising a frame with an endless-chain of hinged shoes adapted to other than as in the light of my disclosure I and the rightful import of the claims which follow.

I claim:

1. A tractor comprising framework, an endless track-chain its lower run adapted to ground support, track-wheels travelable upon ground support provided with twin-track rails raised above the inner surface of the shoes and twin track-wheels travelable upon the ground run of the rails, flexibly resilient means depending below the track surface of the rails adapted to guide the ground run of the endless-chain and control its flexure.

8. In a tractor comprising a frame with an endless-chain of hinged I tread-shoes adapted to ground. support provided with twin-track rails raised above the inner surface of the shoes and load-bearing wheels journalled on the frame travelable upon the ground run of track rails, a flexibly resilient support guide-rail for the upper run of the endless-chain between the twin tracks upon the upper surface of Which rail the chain travels. r

9. In a tractor comprising a frame with an endless-chain of hinged tread-shoes adapted to ground support and provided with twin-tracks raised above the inner surient support guide-rail for the upper run of the endless-chain between the twin-tracks upon the upper surface of which fail the 5 chain travels.

WILLIAM SMYTH; 

